The Sensor Array That Grew Into a Robot Cat

Human brains evolved to pay extra attention to anything that resembles a face. (Scientific term: “facial pareidolia”) [Rongzhong Li] built a robot sensor array with multiple emitters and receivers augmenting a Raspberry Pi camera in the center. When he looked at his sensor array, he saw the face of a cat looking back at him. This started his years-long Petoi OpenCat project to build a feline-inspired body to go with the face.

While the name of the project signals [Rhongzhong]’s eventual intention, he has yet to release project details to the open-source community. But by reading his project page and scrutinizing his YouTube videos (a recent one is embedded below) we can decipher some details. Motion comes via hobby remote-control servos orchestrated by an Arduino. Higher-level functions such as awareness of environment and Alexa integration are handled by a Raspberry Pi 3.

The secret (for now) sauce are the mechanical parts that tie them all together. From impact-absorption spring integrated into the upper leg to how its wrists/ankles articulate. [Rongzhong] believes the current iteration is far too difficult to build and he wants to simplify construction before release. And while we don’t have much information on the software, the sensor array that started it all implies some level of sensor fusion capabilities.

We’ve seen lots of robotic pets, and for some reason there have been far more robotic dogs than cats. Inspiration can come from Boston Dynamics, from Dr. Who, or from… Halloween? We think the lack of cat representation is a missed opportunity for robotic pets. After all, if a robot cat’s voice recognition module fails and a command is ignored… that’s not a bug, it’s a feature of being a cat.

Jimmy_Pop – I found a old metallic dish drainer and turned it upside-down and put kitty’s bowls on top. She sits more comfortably while eating not having to bend down so far and ants and mice either don’t bother climbing or just don’t detect the bowl of food up there. They both are capable to climb, but the metallic narrow legs make it less likely for them to do so. Also no mouse will want to be struggling up the legs while a viscous feline is only moments away from pouncing. However, kitty won’t do anything with ants just watch them at work eating her food.

HIGH TECH METHOD OF ANT MITIGATION (ant genocide?): Raid® makes a gel that when squirted near a path of ants, they ingest it not for themselves but for the queen. They carry it back to her where she does eat it and it immediately kills her. That way the eggs or larvae (and the workers too) is NOT fed and the entire colony is wiped out from starvation. The distressed workers randomly wander about until they eventually starve to death in a few days.The yucky part is watching the workers swarm over your gel. About a day or day and half they are all gone PERMANENTLY, until a new colony moves in next year. The cat wont touch it.
————————–Rongzhong Li – Your robo cat is simply awesome. Makes me stick my tongue out to a certain KIWI HaD’er who thinks my many posts about Boston Dynamic robots where frivolous and pointless because it was way over HaD’ers heads. Now who has egg on their face? :P

Dogs are better if you want a pet that is loving and will play with you on your terms.
Cats are better if you want a pet that doesn’t need constant attention and can deal with you being gone for a day or two.

A robotic anything requires even less attention than a cat so cats pretty much lose their entire advantage.

I think that’s why we don’t see more robotic cats. It’s kind of like if someone came up with a way to make super cheap clones of car models and decided the first thing they wanted to clone was a Kia!

“Dogs are better if you want a pet that is loving and will play with you on your terms.”

That’s what all dog owners say about their subservient crawling slave that’s only held from stabbing you in the back because the only time he’s not too scared to do it’s own thing, is when you’re not home. :) At least cats stab you while looking you straight in the eye. :P

I truly feel sad for you, if you’ve never experienced the joy of a dog that truly and surely loves you. It’s not even unnatural. You’re the alpha in their little pack. They look to you not only for support and companionship, but for love and attention too. The most tragic thing about what you said, is it tells me you’ve never been “part of the pack”. It’s an incredible thing, and it IS real. Dogs. Love. They do if you give them reason to, and it has nothing to do with fear.

Now if they really want realistic walking they should find a way to accurately measure motor torque. Controlling force applied rather than position is the key to making walking robots like Boston Dynamics has.

Servo control is torque control, but it’s open loop from the controller’s point of view since the servo does it independently. With position feedback, the amount of torque applied is in direct proportion to the error in achieved position. Or, you can also pull the same information out by measuring the pulse width of the power going to the motor.

The difficulty is that those little servos can’t handle holding much torque without overheating, so you pretty much have to design the system to be light enough on its feet that the servos can always achieve their intended motions.

However, knowing how analog servos work, you can always reduce torque by reducing the pulse frequency. The issue with that is, the kitty develops parkinson’s disease.

unfortunately the robotic cat did not play with cat toys. and there wasn’t a laser or strings to be seen in the vid. and no fake food (mice, insects, invisible things). it’ll be easy to wait a year or two until these to make appearances — not out of necessity but for showing off programming/building skills and the mimicry.